With recent increase in the size of liquid crystal display devices, the size of color filters used for liquid crystal display devices has also increased. In a process of producing color filters, patterning is performed by photolithography to form colored layers. However, there is a problem that the cost of producing color filters is increased due to the very high price of large photomasks. In response, various kinds of new exposure methods using small masks have been studied.
One example of the exposure methods using small masks is a method (hereinafter, referred to as a “small mask continuous exposure mode”) in which the entire surface of a to-be-exposed substrate is repeatedly exposed while the substrate is being transported, by using an exposure device in which photomasks smaller than the substrate are mounted to exposure heads.
FIG. 15 is a plan view illustrating an exposure method employing the small mask continuous exposure mode, and FIG. 16 is a side view illustrating a positional relationship among a substrate, a photomask, and a blind shutter.
As shown in FIG. 15, a photomask 130 is located relative to a substrate 120. The photomask includes, for example, a plurality of openings 131 for forming dot-shaped colored pixels and photo spacers (hereinafter, also referred to as “PSs”). While the substrate 120 is being transported in a direction indicated by an arrow in FIG. 15, display regions of the substrate 120 are sequentially exposed through the openings 131 to form colored pixels and photo spacers (not shown).
The substrate 120 has display regions 140 in which colored pixels are formed and non-display regions 150 surrounding the circumferences of the display regions 140. The PSs formed in each display region 140 function to maintain a constant interval between a color filter substrate 110 and a TFT substrate which is an opposite substrate when the two substrates are bonded together. The PSs are provided also in each non-display region 150 in some cases (PSs provided in each non-display region 150 are referred to as “dummy PSs” hereinafter). When the color filter substrate 110 and the TFT substrate are bonded together, the dummy PSs serve an important function of maintaining a constant interval between the two substrates at the outside of the display region 140, and thus stabilizing a cell gap (a space containing liquid crystals in a cell).